符号付偶数交点数列 { -4, -6, -2, 10, 12, 8 } 射影交点座標 { (r,-π/4,-R,0) , (r,π/4,-R,0) , (R,π,0,0) , (r,3π/4,R,0) , (r,-3π/4,R,0) , (R,0,0,0) } 交点間中点座標 { 0 , (r,π/2,-R,0) , (r,0,-R,0) , (r,-π/2,-R,0) , 0 , 0 , 0 , (r,-π/2,R,0) , (…